This invention relates to an adjustable mold for casting concrete median barriers and, in particular, to an adjustable mold for precasting median barriers of varying sizes and shapes so that they conform to the actual topography of the road.
As explained in U.S. Pat. No. 4,668,462 to Smith, concrete median barriers have a particular geometry that is designed to minimize the risks to motorists in the event the barrier is struck by a moving vehicle. When the roadway is level, the barrier will be symmetrical, that is, it will have the same profile on the opposing faces of the side walls. Vehicles striking the barrier on either side will be deflected away from the barrier and thus prevented from entering an adjacent lane of traffic. Actual road beds, however, are generally not level and the lanes sometimes converge and diverge in relation to each other. Consequently, the requirements for concrete median barriers at the job site may vary considerably to meet changing road geometries.
One way to fabricate an asymmetrical median barrier is to build a specific or dedicated mold at the job site. After the median section is cast, the mold is generally broken down and the parts discarded. Casting methods using dedicated molds have proven to be both time consuming and extremely expensive.
Attempts have been made to build adjustable metal molds for use at the job site to cast barriers in place. This type of mold is disclosed in U.S. Pat. Nos. 3,792,133 and 4,014,633. These molds generally have at least one adjustable sidewall that provides for limited changes in the profile of the cast section.
Smith, in the previously noted 4,668,462 Pat. provides a reusable mold fixture in which asymmetrical road median sections can be cast. The mold has one fixed sidewall of a desired contour and an opposing adjustable sidewall having a similar contour. The adjustable sidewall is movably mounted in the fixture so that it can be selectively positioned in a vertical plane. Smith utilizes very special split end wall doors to close his mold.
The Smith mold, when set up in the field, operates well when casting asymmetrical barrier sections. The end wall doors, however, are difficult to adjust and align with the side walls of the mold. The mold furthermore can not be adjusted to change the width of the barrier sections. Oftentimes the distance between adjacent road lanes, as well as the elevation of the lane surfaces, will change, and it is desirable to not only alter the sidewall profile of a barrier, but also the width of the section along its length.